Method of processing images captured by digital camera to reduce distortion

ABSTRACT

A method of processing, in a digital camera, an image captured by the camera is provided, which includes locating faces within the captured image by detecting regions of contiguous color which map a hue, saturation and value of the range of human face colors and passing the detected regions through heuristic tests which produce a resulting probability of a face being present in the image, locating eyes of the located faces, and determining if the captured image of the located eyes has been modified by the act of capturing the image. If the image has been modified any unwanted distortions of the located eyes are located in the captured image that have occurred as a result of the act of capturing the image, and the captured image is modified to at least reduce the effect of the unwanted distortions and to produce a modified image.

CROSS REFERENCES TO RELATED APPLICATIONS

This is a Continuation of U.S. application Ser. No. 10/636,224 filed Aug. 8, 2003, which is a Continuation of U.S. application Ser. No. 09/112,742 filed on Jul. 10, 1998. The following Australian provisional patent applications are hereby incorporated by cross-reference. For the purposes of location and identification, US patent applications identified by their US patent application serial numbers (USSN) are listed alongside the Australian applications from which the US patent applications claim the right of priority.

CROSS- US PATENT/PATENT REFERENCED APPLICATION AUSTRALIAN (CLAIMING RIGHT OF PROVISIONAL PRIORITY FROM PATENT AUSTRALIAN APPLICATION NO. PROVISIONAL APPLICATION) PO7991 6,750,901 PO8505 6,476,863 PO7988 6,788,336 PO9395 6,322,181 PO8017 6,597,817 PO8014 6,227,648 PO8025 6,727,948 PO8032 6,690,419 PO7999 6,727,951 PO8030 6,196,541 PO7997 6,195,150 PO7979 6,362,868 PO7978 6,831,681 PO7982 6,431,669 PO7989 6,362,869 PO8019 6,472,052 PO7980 6,356,715 PO8018 6,894,694 PO7938 6,636,216 PO8016 6,366,693 PO8024 6,329,990 PO7939 6,459,495 PO8501 6,137,500 PO8500 6,690,416 PO7987 7,050,143 PO8022 6,398,328 PO8497 7,110,024 PO8020 6,431,704 PO8504 6,879,341 PO8000 6,415,054 PO7934 6,665,454 PO7990 6,542,645 PO8499 6,486,886 PO8502 6,381,361 PO7981 6,317,192 PO7986 6,850,274 PO8026 6,646,757 PO8028 6,624,848 PO9394 6,357,135 PO9397 6,271,931 PO9398 6,353,772 PO9399 6,106,147 PO9400 6,665,008 PO9401 6,304,291 PO9403 6,305,770 PO9405 6,289,262 PP0959 6,315,200 PP1397 6,217,165 PP2370 6,786,420 PO8003 6,350,023 PO8005 6,318,849 PO8066 6,227,652 PO8072 6,213,588 PO8040 6,213,589 PO8071 6,231,163 PO8047 6,247,795 PO8035 6,394,581 PO8044 6,244,691 PO8063 6,257,704 PO8057 6,416,168 PO8056 6,220,694 PO8069 6,257,705 PO8049 6,247,794 PO8036 6,234,610 PO8048 6,247,793 PO8070 6,264,306 PO8067 6,241,342 PO8001 6,247,792 PO8038 6,264,307 PO8033 6,254,220 PO8002 6,234,611 PO8068 6,302,528 PO8062 6,283,582 PO8034 6,239,821 PO8039 6,338,547 PO8041 6,247,796 PO8004 6,557,977 PO8037 6,390,603 PO8043 6,362,843 PO8042 6,293,653 PO8064 6,312,107 PO9389 6,227,653 PO9391 6,234,609 PP0888 6,238,040 PP0891 6,188,415 PP0890 6,227,654 PP0873 6,209,989 PP0993 6,247,791 PP0890 6,336,710 PP1398 6,217,153 PP2592 6,416,167 PP2593 6,243,113 PP3991 6,283,581 PP3987 6,247,790 PP3985 6,260,953 PP3983 6,267,469 PO7935 6,224,780 PO7936 6,235,212 PO7937 6,280,643 PO8061 6,284,147 PO8054 6,214,244 PO8065 6,071,750 PO8055 6,267,905 PO8053 6,251,298 PO8078 6,258,285 PO7933 6,225,138 PO7950 6,241,904 PO7949 6,299,786 PO8060 6,866,789 PO8059 6,231,773 PO8073 6,190,931 PO8076 6,248,249 PO8075 6,290,862 PO8079 6,241,906 PO8050 6,565,762 PO8052 6,241,905 PO7948 6,451,216 PO7951 6,231,772 PO8074 6,274,056 PO7941 6,290,861 PO8077 6,248,248 PO8058 6,306,671 PO8051 6,331,258 PO8045 6,110,754 PO7952 6,294,101 PO8046 6,416,679 PO9390 6,264,849 PO9392 6,254,793 PP0889 6,235,211 PP0887 6,491,833 PP0882 6,264,850 PP0874 6,258,284 PP1396 6,312,615 PP3989 6,228,668 PP2591 6,180,427 PP3990 6,171,875 PP3986 6,267,904 PP3984 6,245,247 PP3982 6,315,914 PP0895 6,231,148 PP0869 6,293,658 PP0887 6,614,560 PP0885 6,238,033 PP0884 6,312,070 PP0886 6,238,111 PP0877 6,378,970 PP0878 6,196,739 PP0883 6,270,182 PP0880 6,152,619 PO8006 6,087,638 PO8007 6,340,222 PO8010 6,041,600 PO8011 6,299,300 PO7947 6,067,797 PO7944 6,286,935 PO7946 6,044,646 PP0894 6,382,769

FIELD OF INVENTION

The present invention relates to an image processing method and apparatus and, in particular, discloses a process for correcting for flash induced distortions in a Digital Image Camera.

The present invention further relates to the field of digital image processing and in particular, the field of processing of images taken via a digital camera.

BACKGROUND OF THE INVENTION

Recently, digital cameras have become increasingly popular. These cameras normally operate by means of imaging a desired image utilizing a charge coupled device (CCD) array and storing the imaged scene on an electronic storage medium for later down loading onto a computer system for subsequent manipulation and printing out. Normally, when utilizing a computer system to print out an image, sophisticated software may be available to manipulate the image in accordance with requirements.

Unfortunately such systems require significant post processing of a captured image and normally present the image in an orientation in which it was taken, relying on the post processing process to perform any necessary or required modifications of the captured image. Further, much of the environmental information available when the picture was taken is lost.

SUMMARY OF THE INVENTION

It is an object of the present invention to utilize flash information in a digital image camera for processing digital images.

In accordance with a first aspect of the present invention there is provided a method of processing an image captured utilizing a digital camera and a flash said method comprising the steps of:

-   -   (a) locating distortions of said captured image due to the         utilization of said flash;     -   (b) retouching said image so as to locally reduce the effect of         said distortions.

In accordance with the second aspect of the present invention there is provided a digital camera having reduced flash distortion effects on captured images comprising;

-   -   (a) a digital image capture means for the capture of images;     -   (b) a distortion location means for locating flash induced color         distortions in the captured image; and     -   (c) image correction means connected to said distortion location         means and said digital image capture means and adapted to         process said captured image to reduce the effects of said         distortions;     -   (d) display means connected to said image correction means for         displaying said captured image having reduced flash distortion         effects.

In another broad form, the invention includes a method of processing, in a digital camera, an image captured by the camera, the method including:

-   -   determining if the captured image has been modified by the act         of capturing the image, and if so,         -   locating any unwanted distortions of in the captured image             that have occurred as a result of the act of capturing the             image, and         -   modifying the captured image to at least reduce the effect             of the unwanted distortions and to produce a modified image.

The determining step may include determining if a flash was used in capturing the image.

The locating step may include automatically locating faces within an image.

Unwanted distortions may include “red-eye” effects, reflections in the captured image and modification of the colors captured.

At least one predetermined image may be added to the captured image if it is determined that the image has or has not been modified by the act of capture.

In a further broad form, the invention includes a digital camera including:

-   -   an image sensor that captures images on demand of a user;     -   at least one onboard processor configured to         -   determine if the captured image has been modified by the act             of capturing the image, and if so,         -   locate any unwanted distortions of in the captured image             that have occurred as a result of the act of capturing the             image, and         -   modify the captured image to at least reduce the effect of             the unwanted distortions to produce a modified image.

The at least one onboard processor may be configured to determine if a flash was used in capturing the image.

The at least one onboard processor may be configured to locate faces within the captured image.

Unwanted distortions may include “red-eye” effects, reflections in the captured image and modification of the colors captured.

At least one predetermined image may be added to the captured image by the at least one processor if it is determined that the image has or has not been modified by the act of capture.

Preferably the camera includes a display upon which modified and/or unmodified images may be displayed.

Preferably the camera includes memory in which captured images and/or modified images are stored.

BRIEF DESCRIPTION OF DRAWING

Notwithstanding any other forms that may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 illustrates the process of capturing and outputting an image; and

FIG. 2 illustrates the process of red-eye removal.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

The preferred embodiment is preferably implemented through suitable programming of a hand held camera device such as that described in patent application having applicant's reference (ART01) U.S. Ser. No. 09/113,060 filed concurrently herewith by the present applicant the content of which is hereby specifically incorporated by cross reference.

The aforementioned patent specification discloses a camera system, hereinafter known as an “Artcam” type camera, wherein sensed images can be directly printed out by an Artcam portable camera unit. Further, the aforementioned specification discloses means and methods for performing various manipulations on images captured by the camera sensing device leading to the production of various effects in any output image. The manipulations are disclosed to be highly flexible in nature and can be implemented through the insertion into the Artcam of cards having encoded thereon various instructions for the manipulation of images, the cards hereinafter being known as Artcards. The Artcam further has significant onboard processing power in an Artcam Central Processor unit (ACP) that is interconnected to a memory device for the storage of important data and images.

As disclosed in U.S. Ser. No. 09/113,060 (issued as U.S. Pat. No. 6,750,901), the Artcards contain, on one surface encoded information and on the other surface, contain an image distorted by the particular effect produced by the Artcard. The Artcard is inserted in an Artcard reader in the side of camera and, upon insertion, results in an output image being distorted in the same manner as the distortion appearing on the surface of Artcard.

One important form of processing is the removal of “red-eye” effects that can result in captured images as result of utilization of a flash.

Turning now to FIG. 1, in the preferred embodiment, the image 2 as originally captured by the CCD device is subject to a processing step 3 when a flash has been utilized so as to produce a processed output image for printing.

Turning now to FIG. 2, there is illustrated in more detail, one particular image processing algorithm 10 which can be utilized when a flash has been utilized in capturing an image by a CCD device. The algorithm is preferably only utilized when a flash was used 11 to take the picture captured by the CCD. The purpose of the algorithm is to reduce the image effects due to the utilization of the flash. Such image effects can include the well known “red-eye” effect of individual eyes appearing red in a photographic image. Other effects such as flash reflections off reflective surfaces can also be separately processed utilizing other algorithms. The first step 12 in eliminating red-eye effects in the images is to determine the faces within the image. The face detection process 12 can proceed by detecting regions of contiguous color which map the hue, saturation and value (HSV) of the range of human face colors under the range of normal lighting encountered after any other applied image enhancements or hue corrections. The detected regions can then be passed through various heuristic tests including determining the presence of eyes, mouth, overall shape and overlap. The heuristic tests produce a resulting probability of a face being present in the image and where this is above a threshold, a face is determined to be located in the image.

Once a face has been determined within an image, the eyes are located within the face in step 13. Each eye in step 12 is then independently processed to determine its special range of colors so as determine whether a red-eye removal process is required instep 14.

If the red-eye removal process 14 is required, a retouching algorithm 15 is applied to the eye area so as to reduce the red saturation whilst simultaneously not introducing any discontinuities or likely artifacts in the output image. Of course, many different techniques could be utilized including a form of Gaussian alteration around a central point of the eye. Finally, the image is written in step 16 in its updated form, back to the memory device of the ACP.

Preferably, any other retouching algorithms including remapping colors affected by the spectral nature of the flashlight are also utilized at this time.

Alternatively, the Artcard inserted could have a number of manipulations applied to the image that are specific to the flash setting. For example, clip arts containing candles, light globes etc could be inserted in an image utilizing a flash and large suns inserted in non-flash images.

It would be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiment without departing from the spirit or scope of the invention as broadly described. The present embodiment is, therefore, to be considered in all respects to be illustrative and not restrictive.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Of course many different devices could be used. However presently popular ink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption. This is approximately 100 times that required for high speed, and stems from the energy-inefficient means of drop ejection. This involves the rapid boiling of water to produce a vapor bubble that expels the ink. Water has a very high heat capacity, and must be superheated in thermal ink jet applications. This leads to an efficiency of around 0.02%, from electricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size and cost. Piezoelectric crystals have a very small deflection at reasonable drive voltages, and therefore require a large area for each nozzle. Also, each piezoelectric actuator must be connected to its drive circuit on a separate substrate. This is not a significant problem at the current limit of around 300 nozzles per print head, but is a major impediment to the fabrication of pagewidth print heads with 19,200 nozzles.

Ideally, the ink jet technologies used meet the stringent requirements of in-camera digital color printing and other high quality, high speed, low cost printing applications. To meet the requirements of digital photography, new ink jet technologies have been created. The target features include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systems described below with differing levels of difficulty. Forty-five different ink jet technologies have been developed by the Assignee to give a wide range of choices for high volume manufacture. These technologies form part of separate applications assigned to the present Assignee as set out in the table under the heading Cross References to Related Applications.

The ink jet designs shown here are suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems

For ease of manufacture using standard process equipment, the print head is designed to be a monolithic 0.5 micron CMOS chip with MEMS post processing. For color photographic applications, the print head is 100 mm long, with a width that depends upon the ink jet type. The smallest print head designed is IJ38, which is 0.35 mm wide, giving a chip area of 35 square mm. The print heads each contain 19,200 nozzles plus data and control circuitry.

Ink is supplied to the back of the print head by injection molded plastic ink channels. The molding requires 50 micron features, which can be created using a lithographically micromachined insert in a standard injection molding tool. Ink flows through holes etched through the wafer to the nozzle chambers fabricated on the front surface of the wafer. The print head is connected to the camera circuitry by tape automated bonding.

Tables of Drop-on-Demand Ink Jets

Eleven important characteristics of the fundamental operation of individual ink jet nozzles have been identified. These characteristics are largely orthogonal, and so can be elucidated as an eleven dimensional matrix. Most of the eleven axes of this matrix include entries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of ink jet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of ink jet nozzle. While not all of the possible combinations result in a viable ink jet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain ink jet types have been investigated in detail. These are designated IJ01 to IJ45 which match the docket numbers in the table under the heading Cross References to Relation Applications.

Other ink jet configurations can readily be derived from these forty-five examples by substituting alternative configurations along one or more of the 11 axes. Most of the IJ01 to IJ45 examples can be made into ink jet print heads with characteristics superior to any currently available ink jet technology.

Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The IJ01 to IJ45 series are also listed in the examples column. In some cases, a print technology may be listed more than once in a table, where it shares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Home printers, Office network printers, Short run digital printers, Commercial print systems, Fabric printers, Pocket printers, Internet WWW printers, Video printers, Medical imaging, Wide format printers, Notebook PC printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrix are set out in the following tables.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Thermal An electrothermal Large force High power Canon bubble heater heats the generated Ink carrier Bubblejet 1979 ink to above Simple limited to water Endo et al GB boiling point, construction Low patent 2,007,162 transferring No moving efficiency Xerox significant heat to parts High heater-in-pit the aqueous ink. A Fast temperatures 1990 Hawkins et bubble nucleates operation required al U.S. Pat. No. and quickly forms, Small chip High 4,899,181 expelling the ink. area required for mechanical Hewlett- The efficiency of actuator stress Packard TIJ the process is low, Unusual 1982 Vaught et with typically less materials al U.S. Pat. No. than 0.05% of the required 4,490,728 electrical energy Large drive being transformed transistors into kinetic energy Cavitation of the drop. causes actuator failure Kogation reduces bubble formation Large print heads are difficult to fabricate Piezo- A piezoelectric Low power Very large Kyser et al electric crystal such as consumption area required for U.S. Pat. No. 3,946,398 lead lanthanum Many ink actuator Zoltan U.S. Pat. No. zirconate (PZT) is types can be Difficult to 3,683,212 electrically used integrate with 1973 activated, and Fast electronics Stemme U.S. Pat. No. either expands, operation High 3,747,120 shears, or bends to High voltage drive Epson apply pressure to efficiency transistors Stylus the ink, ejecting required Tektronix drops. Full IJ04 pagewidth print heads impractical due to actuator size Requires electrical poling in high field strengths during manufacture Electro- An electric field is Low power Low Seiko strictive used to activate consumption maximum strain Epson, Usui et electrostriction in Many ink (approx. 0.01%) all JP 253401/96 relaxor materials types can be Large area IJ04 such as lead used required for lanthanum Low actuator due to zirconate titanate thermal low strain (PLZT) or lead expansion Response magnesium Electric speed is niobate (PMN). field strength marginal (~10 μs) required High (approx. 3.5 V/μm) voltage drive can be transistors generated required without Full difficulty pagewidth print Does not heads require electrical impractical due poling to actuator size Ferro- An electric field is Low power Difficult to IJ04 electric used to induce a consumption integrate with phase transition Many ink electronics between the types can be Unusual antiferroelectric used materials such as (AFE) and Fast PLZSnT are ferroelectric (FE) operation (<1 μs) required phase. Perovskite Relatively Actuators materials such as high longitudinal require a large tin modified lead strain area lanthanum High zirconate titanate efficiency (PLZSnT) exhibit Electric large strains of up field strength of to 1% associated around 3 V/μm with the AFE to can be readily FE phase provided transition. Electro- Conductive plates Low power Difficult to IJ02, IJ04 static are separated by a consumption operate plates compressible or Many ink electrostatic fluid dielectric types can be devices in an (usually air). Upon used aqueous application of a Fast environment voltage, the plates operation The attract each other electrostatic and displace ink, actuator will causing drop normally need to ejection. The be separated conductive plates from the ink may be in a comb Very large or honeycomb area required to structure, or achieve high stacked to increase forces the surface area High and therefore the voltage drive force. transistors may be required Full pagewidth print heads are not competitive due to actuator size Electro- A strong electric Low current High 1989 Saito static field is applied to consumption voltage required et al, U.S. Pat. No. pull on the ink, whereupon Low May be 4,799,068 ink electrostatic temperature damaged by 1989 Miura attraction sparks due to air et al, U.S. Pat. No. accelerates the ink breakdown 4,810,954 towards the print Required Tone-jet medium. field strength increases as the drop size decreases High voltage drive transistors required Electrostatic field attracts dust Permanent An electromagnet Low power Complex IJ07, IJ10 magnet directly attracts a consumption fabrication electro- permanent magnet, Many ink Permanent magnetic displacing ink and types can be magnetic causing drop used material such as ejection. Rare Fast Neodymium Iron earth magnets with operation Boron (NdFeB) a field strength High required. around 1 Tesla can efficiency High local be used. Examples Easy currents required are: Samarium extension from Copper Cobalt (SaCo) and single nozzles to metalization magnetic materials pagewidth print should be used in the neodymium heads for long iron boron family electromigration (NdFeB, lifetime and low NdDyFeBNb, resistivity NdDyFeB, etc) Pigmented inks are usually infeasible Operating temperature limited to the Curie temperature (around 540 K) Soft A solenoid Low power Complex IJ01, IJ05, magnetic induced a consumption fabrication IJ08, IJ10, IJ12, core magnetic field in a Many ink Materials IJ14, IJ15, IJ17 electro- soft magnetic core types can be not usually magnetic or yoke fabricated used present in a from a ferrous Fast CMOS fab such material such as operation as NiFe, electroplated iron High CoNiFe, or CoFe alloys such as efficiency are required CoNiFe [1], CoFe, Easy High local or NiFe alloys. extension from currents required Typically, the soft single nozzles to Copper magnetic material pagewidth print metalization is in two parts, heads should be used which are for long normally held electromigration apart by a spring. lifetime and low When the solenoid resistivity is actuated, the two Electroplating parts attract, is required displacing the ink. High saturation flux density is required (2.0-2.1 T is achievable with CoNiFe [1]) Lorenz The Lorenz force Low power Force acts IJ06, IJ11, force acting on a current consumption as a twisting IJ13, IJ16 carrying wire in a Many ink motion magnetic field is types can be Typically, utilized. used only a quarter of This allows the Fast the solenoid magnetic field to operation length provides be supplied High force in a useful externally to the efficiency direction print head, for Easy High local example with rare extension from currents required earth permanent single nozzles to Copper magnets. pagewidth print metalization Only the current heads should be used carrying wire need for long be fabricated on electromigration the print-head, lifetime and low simplifying resistivity materials Pigmented requirements. inks are usually infeasible Magneto- The actuator uses Many ink Force acts Fischenbeck, striction the giant types can be as a twisting U.S. Pat. No. magnetostrictive used motion 4,032,929 effect of materials Fast Unusual IJ25 such as Terfenol-D operation materials such as (an alloy of Easy Terfenol-D are terbium, extension from required dysprosium and single nozzles to High local iron developed at pagewidth print currents required the Naval heads Copper Ordnance High force metalization Laboratory, hence is available should be used Ter-Fe-NOL). For for long best efficiency, the electromigration actuator should be lifetime and low pre-stressed to resistivity approx. 8 MPa. Pre- stressing may be required Surface Ink under positive Low power Requires Silverbrook, tension pressure is held in consumption supplementary EP 0771 658 A2 reduction a nozzle by surface Simple force to effect and related tension. The construction drop separation patent surface tension of No unusual Requires applications the ink is reduced materials special ink below the bubble required in surfactants threshold, causing fabrication Speed may the ink to egress High be limited by from the nozzle. efficiency surfactant Easy properties extension from single nozzles to pagewidth print heads Viscosity The ink viscosity Simple Requires Silverbrook, reduction is locally reduced construction supplementary EP 0771 658 A2 to select which No unusual force to effect and related drops are to be materials drop separation patent ejected. A required in Requires applications viscosity reduction fabrication special ink can be achieved Easy viscosity electrothermally extension from properties with most inks, but single nozzles to High speed special inks can be pagewidth print is difficult to engineered for a heads achieve 100:1 viscosity Requires reduction. oscillating ink pressure A high temperature difference (typically 80 degrees) is required Acoustic An acoustic wave Can operate Complex 1993 is generated and without a nozzle drive circuitry Hadimioglu et focussed upon the plate Complex al, EUP 550,192 drop ejection fabrication 1993 Elrod region. Low et al, EUP efficiency 572,220 Poor control of drop position Poor control of drop volume Thermo- An actuator which Low power Efficient IJ03, IJ09, elastic relies upon consumption aqueous IJ17, IJ18, IJ19, bend differential Many ink operation IJ20, IJ21, IJ22, actuator thermal expansion types can be requires a IJ23, IJ24, IJ27, upon Joule heating used thermal insulator IJ28, IJ29, IJ30, is used. Simple on the hot side IJ31, IJ32, IJ33, planar Corrosion IJ34, IJ35, IJ36, fabrication prevention can IJ37, IJ38, IJ39, Small chip be difficult IJ40, IJ41 area required for Pigmented each actuator inks may be Fast infeasible, as operation pigment particles High may jam the efficiency bend actuator CMOS compatible voltages and currents Standard MEMS processes can be used Easy extension from single nozzles to pagewidth print heads High A material with a High force Requires IJ09, IJ17, CTE very high can be generated special material IJ18, IJ20, IJ21, thermo- coefficient of Three (e.g. PTFE) IJ22, IJ23, IJ24, elastic thermal expansion methods of Requires a IJ27, IJ28, IJ29, actuator (CTE) such as PTFE deposition PTFE deposition IJ30, IJ31, IJ42, polytetrafluoroethylene are under process, which is IJ43, IJ44 (PTFE) is development: not yet standard used. As high CTE chemical vapor in ULSI fabs materials are deposition PTFE usually non- (CVD), spin deposition conductive, a coating, and cannot be heater fabricated evaporation followed with from a conductive PTFE is a high temperature material is candidate for (above 350° C.) incorporated. A 50 μm low dielectric processing long PTFE constant Pigmented bend actuator with insulation in inks may be polysilicon heater ULSI infeasible, as and 15 mW power Very low pigment particles input can provide power may jam the 180 μN force and consumption bend actuator 10 μm deflection. Many ink Actuator motions types can be include: used Bend Simple Push planar Buckle fabrication Rotate Small chip area required for each actuator Fast operation High efficiency CMOS compatible voltages and currents Easy extension from single nozzles to pagewidth print heads Conductive A polymer with a High force Requires IJ24 polymer high coefficient of can be generated special materials thermo- thermal expansion Very low development elastic (such as PTFE) is power (High CTE actuator doped with consumption conductive conducting Many ink polymer) substances to types can be Requires a increase its used PTFE deposition conductivity to Simple process, which is about 3 orders of planar not yet standard magnitude below fabrication in ULSI fabs that of copper. The Small chip PTFE conducting area required for deposition polymer expands each actuator cannot be when resistively Fast followed with heated. operation high temperature Examples of High (above 350° C.) conducting efficiency processing dopants include: CMOS Evaporation Carbon nanotubes compatible and CVD Metal fibers voltages and deposition Conductive currents techniques polymers such as Easy cannot be used doped extension from Pigmented polythiophene single nozzles to inks may be Carbon granules pagewidth print infeasible, as heads pigment particles may jam the bend actuator Shape A shape memory High force Fatigue IJ26 memory alloy such as TiNi is available limits maximum alloy (also known as (stresses of number of cycles Nitinol - Nickel hundreds of Low strain Titanium alloy MPa) (1%) is required developed at the Large strain to extend fatigue Naval Ordnance is available resistance Laboratory) is (more than 3%) Cycle rate thermally switched High limited by heat between its weak corrosion removal martensitic state resistance Requires and its high Simple unusual stiffness austenic construction materials (TiNi) state. The shape of Easy The latent the actuator in its extension from heat of martensitic state is single nozzles to transformation deformed relative pagewidth print must be to the austenic heads provided shape. The shape Low High change causes voltage current operation ejection of a drop. operation Requires pre-stressing to distort the martensitic state Linear Linear magnetic Linear Requires IJ12 Magnetic actuators include Magnetic unusual Actuator the Linear actuators can be semiconductor Induction Actuator constructed with materials such as (LIA), Linear high thrust, long soft magnetic Permanent Magnet travel, and high alloys (e.g. Synchronous efficiency using CoNiFe) Actuator planar Some (LPMSA), Linear semiconductor varieties also Reluctance fabrication require Synchronous techniques permanent Actuator (LRSA), Long magnetic Linear Switched actuator travel is materials such as Reluctance available Neodymium iron Actuator (LSRA), Medium boron (NdFeB) and the Linear force is available Requires Stepper Actuator Low complex multi- (LSA). voltage phase drive operation circuitry High current operation

Description Advantages Disadvantages Examples BASIC OPERATION MODE Actuator This is the Simple Drop Thermal ink directly simplest mode of operation repetition rate is jet pushes operation: the No external usually limited Piezoelectric ink actuator directly fields required to around 10 kHz. ink jet supplies sufficient Satellite However, IJ01, IJ02, kinetic energy to drops can be this is not IJ03, IJ04, IJ05, expel the drop. avoided if drop fundamental to IJ06, IJ07, IJ09, The drop must velocity is less the method, but IJ11, IJ12, IJ14, have a sufficient than 4 m/s is related to the IJ16, IJ20, IJ22, velocity to Can be refill method IJ23, IJ24, IJ25, overcome the efficient, normally used IJ26, IJ27, IJ28, surface tension. depending upon All of the IJ29, IJ30, IJ31, the actuator used drop kinetic IJ32, IJ33, IJ34, energy must be IJ35, IJ36, IJ37, provided by the IJ38, IJ39, IJ40, actuator IJ41, IJ42, IJ43, Satellite IJ44 drops usually form if drop velocity is greater than 4.5 m/s Proximity The drops to be Very simple Requires Silverbrook, printed are print head close proximity EP 0771 658 A2 selected by some fabrication can between the and related manner (e.g. be used print head and patent thermally induced The drop the print media applications surface tension selection means or transfer roller reduction of does not need to May require pressurized ink). provide the two print heads Selected drops are energy required printing alternate separated from the to separate the rows of the ink in the nozzle drop from the image by contact with the nozzle Monolithic print medium or a color print heads transfer roller. are difficult Electro- The drops to be Very simple Requires Silverbrook, static printed are print head very high EP 0771 658 A2 pull on selected by some fabrication can electrostatic field and related ink manner (e.g. be used Electrostatic patent thermally induced The drop field for small applications surface tension selection means nozzle sizes is Tone-Jet reduction of does not need to above air pressurized ink). provide the breakdown Selected drops are energy required Electrostatic separated from the to separate the field may ink in the nozzle drop from the attract dust by a strong electric nozzle field. Magnetic The drops to be Very simple Requires Silverbrook, pull on printed are print head magnetic ink EP 0771 658 A2 ink selected by some fabrication can Ink colors and related manner (e.g. be used other than black patent thermally induced The drop are difficult applications surface tension selection means Requires reduction of does not need to very high pressurized ink). provide the magnetic fields Selected drops are energy required separated from the to separate the ink in the nozzle drop from the by a strong nozzle magnetic field acting on the magnetic ink. Shutter The actuator High speed Moving IJ13, IJ17, moves a shutter to (>50 kHz) parts are IJ21 block ink flow to operation can be required the nozzle. The ink achieved due to Requires pressure is pulsed reduced refill ink pressure at a multiple of the time modulator drop ejection Drop timing Friction and frequency. can be very wear must be accurate considered The Stiction is actuator energy possible can be very low Shuttered The actuator Actuators Moving IJ08, IJ15, grill moves a shutter to with small travel parts arre IJ18, IJ19 block ink flow can be used required through a grill to Actuator Requires the nozzle. The with small force ink pressure shutter movement can be used modulator need only be equal High speed Friction and to the width of the (>50 kHz) wear must be grill holes. operation can be considered achieved Stiction is possible Pulsed A pulsed magnetic Extremely Requires an IJ10 magnetic field attracts an low energy external pulsed pull on ink pusher at the operation is magnetic field ink drop ejection possible Requires pusher frequency. An No heat special material actuator controls a dissipation for both the catch, which problem actuator and the prevents the ink ink pusher pusher from Complex moving when a construction drop is not to be ejected. AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) None The actuator Simplicity Drop Most ink directly fires the of construction ejection energy jets, including ink drop, and there Simplicity must be supplied piezoelectric and is no external field of operation by individual thermal bubble. or other Small nozzle actuator IJ01, IJ02, mechanism physical size IJ03, IJ04,IJ05, required. IJ07, IJ09,IJ11, IJ12, IJ14,IJ20, IJ22, IJ23,IJ24, IJ25, IJ26,IJ27, IJ28, IJ29,IJ30, IJ31, IJ32,IJ33, IJ34, IJ35,IJ36, IJ37, IJ38,IJ39, IJ40, IJ41,IJ42, IJ43, IJ44 BASIC OPERATION MODE Oscillating The ink pressure Oscillating Requires Silverbrook, ink oscillates, ink pressure can external ink EP 0771 658 A2 pressure providing much of provide a refill pressure and related (including the drop ejection pulse, allowing oscillator patent acoustic energy. The higher operating Ink pressure applications stimulation) actuator selects speed phase and IJ08, IJ13, which drops are to The amplitude must IJ15, IJ17, IJ18, be fired by actuators may be carefully IJ19, IJ21 selectively operate with controlled blocking or much lower Acoustic enabling nozzles. energy reflections in the The ink pressure Acoustic ink chamber oscillation may be lenses can be must be achieved by used to focus the designed for vibrating the print sound on the head, or preferably nozzles by an actuator in the ink supply. Media The print head is Low power Precision Silverbrook, proximity placed in close High assembly EP 0771 658 A2 proximity to the accuracy required and related print medium. Simple print Paper fibers patent Selected drops head may cause applications protrude from the construction problems print head further Cannot than unselected print on rough drops, and contact substrates the print medium. The drop soaks into the medium fast enough to cause drop separation. Transfer Drops are printed High Bulky Silverbrook, roller to a transfer roller accuracy Expensive EP 0771 658 A2 instead of straight Wide range Complex and related to the print of print construction patent medium. A substrates can be applications transfer roller can used Tektronix also be used for Ink can be hot melt proximity drop dried on the piezoelectric ink separation. transfer roller jet Any of the IJ series Electro- An electric field is Low power Field Silverbrook, static used to accelerate Simple print strength required EP 0771 658 A2 selected drops head for separation of and related towards the print construction small drops is patent medium. near or above air applications breakdown Tone-Jet Direct A magnetic field is Low power Requires Silverbrook, magnetic used to accelerate Simple print magnetic ink EP 0771 658 A2 field selected drops of head Requires and related magnetic ink construction strong magnetic patent towards the print field applications medium. Cross The print head is Does not Requires IJ06, IJ16 magnetic placed in a require magnetic external magnet field constant magnetic materials to be Current field. The Lorenz integrated in the densities may be force in a current print head high, resulting in carrying wire is manufacturing electromigration used to move the process problems actuator. Pulsed A pulsed magnetic Very low Complex IJ10 magnetic field is used to power operation print head field cyclically attract a is possible construction paddle, which Small print Magnetic pushes on the ink. head size materials A small actuator required in print moves a catch, head which selectively prevents the paddle from moving.

ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Description Advantages Disadvantages Examples None No actuator Operational Many Thermal mechanical simplicity actuator Bubble Ink jet amplification is mechanisms IJ01, IJ02, used. The actuator have insufficient IJ06, IJ07, IJ16, directly drives the travel, or IJ25, IJ26 drop ejection insufficient process. force, to efficiently drive the drop ejection process Differential An actuator Provides High Piezoelectric expansion material expands greater travel in stresses are IJ03, IJ09, bend more on one side a reduced print involved IJ17, IJ18, IJ19, actuator than on the other. head area Care must IJ20, IJ21, IJ22, The expansion be taken that the IJ23, IJ24, IJ27, may be thermal, materials do not IJ29, IJ30, IJ31, piezoelectric, delaminate IJ32, IJ33, IJ34, magnetostrictive, Residual IJ35, IJ36, IJ37, or other bend resulting IJ38, IJ39, IJ42, mechanism. The from high IJ43, IJ44 bend actuator temperature or converts a high high stress force low travel during formation actuator mechanism to high travel, lower force mechanism. Transient A trilayer bend Very good High IJ40, IJ41 bend actuator where the temperature stresses are actuator two outside layers stability involved are identical. This High speed, Care must cancels bend due as a new drop be taken that the to ambient can be fired materials do not temperature and before heat delaminate residual stress. The dissipates actuator only Cancels responds to residual stress of transient heating of formation one side or the other. Reverse The actuator loads Better Fabrication IJ05, IJ11 spring a spring. When the coupling to the complexity actuator is turned ink High stress off, the spring in the spring releases. This can reverse the force/distance curve of the actuator to make it compatible with the force/time requirements of the drop ejection. Actuator A series of thin Increased Increased Some stack actuators are travel fabrication piezoelectric ink stacked. This can Reduced complexity jets be appropriate drive voltage Increased IJ04 where actuators possibility of require high short circuits due electric field to pinholes strength, such as electrostatic and piezoelectric actuators. Multiple Multiple smaller Increases Actuator IJ12, IJ13, actuators actuators are used the force forces may not IJ18, IJ20, IJ22, simultaneously to available from add linearly, IJ28, IJ42, IJ43 move the ink. Each an actuator reducing actuator need Multiple efficiency provide only a actuators can be portion of the positioned to force required. control ink flow accurately Linear A linear spring is Matches Requires IJ15 Spring used to transform a low travel print head area motion with small actuator with for the spring travel and high higher travel force into a longer requirements travel, lower force Non-contact motion. method of motion transformation Coiled A bend actuator is Increases Generally IJ17, IJ21, actuator coiled to provide travel restricted to IJ34, IJ35 greater travel in a Reduces planar reduced chip area. chip area implementations Planar due to extreme implementations fabrication are relatively difficulty in easy to fabricate. other orientations. Flexure A bend actuator Simple Care must IJ10, IJ19, bend has a small region means of be taken not to IJ33 actuator near the fixture increasing travel exceed the point, which flexes of a bend elastic limit in much more readily actuator the flexure area than the remainder Stress of the actuator. distribution is The actuator very uneven flexing is Difficult to effectively accurately model converted from an with finite even coiling to an element analysis angular bend, resulting in greater travel of the actuator tip. Catch The actuator Very low Complex IJ10 controls a small actuator energy construction catch. The catch Very small Requires either enables or actuator size external force disables movement Unsuitable of an ink pusher for pigmented that is controlled inks in a bulk manner. Gears Gears can be used Low force, Moving IJ13 to increase travel low travel parts are at the expense of actuators can be required duration. Circular used Several gears, rack and Can be actuator cycles pinion, ratchets, fabricated using are required and other gearing standard surface More methods can be MEMS complex drive used. processes electronics Complex construction Friction, friction, and wear are possible Buckle A buckle plate can Very fast Must stay S. Hirata et plate be used to change movement within elastic al, “An Ink-jet a slow actuator achievable limits of the Head Using into a fast motion. materials for Diaphragm It can also convert long device life Microactuator”, a high force, low High Proc. IEEE travel actuator into stresses involved MEMS, February a high travel, Generally 1996, pp 418-423. medium force high power IJ18, IJ27 motion. requirement Tapered A tapered Linearizes Complex IJ14 magnetic magnetic pole can the magnetic construction pole increase travel at force/distance the expense of curve force. Lever A lever and Matches High stress IJ32, IJ36, fulcrum is used to low travel around the IJ37 transform a motion actuator with fulcrum with small travel higher travel and high force into requirements a motion with Fulcrum longer travel and area has no lower force. The linear lever can also movement, and reverse the can be used for a direction of travel. fluid seal Rotary The actuator is High Complex IJ28 impeller connected to a mechanical construction rotary impeller. A advantage Unsuitable small angular The ratio of for pigmented deflection of the force to travel of inks actuator results in the actuator can a rotation of the be matched to impeller vanes, the nozzle which push the ink requirements by against stationary varying the vanes and out of number of the nozzle. impeller vanes Acoustic A refractive or No moving Large area 1993 lens diffractive (e.g. parts required Hadimioglu et zone plate) Only al, EUP 550,192 acoustic lens is relevant for 1993 Elrod used to concentrate acoustic ink jets et al, EUP sound waves. 572,220 Sharp A sharp point is Simple Difficult to Tone-jet conductive used to concentrate construction fabricate using point an electrostatic standard VLSI field. processes for a surface ejecting ink-jet Only relevant for electrostatic ink jets

ACTUATOR MOTION Description Advantages Disadvantages Examples Volume The volume of the Simple High energy Hewlett- expansion actuator changes, construction in is typically Packard Thermal pushing the ink in the case of required to Ink jet all directions. thermal ink jet achieve volume Canon expansion. This Bubblejet leads to thermal stress, cavitation, and kogation in thermal ink jet implementations Linear, The actuator Efficient High IJ01, IJ02, normal moves in a coupling to ink fabrication IJ04, IJ07, IJ11, to chip direction normal to drops ejected complexity may IJ14 surface the print head normal to the be required to surface. The surface achieve nozzle is typically perpendicular in the line of motion movement. Parallel The actuator Suitable for Fabrication IJ12, IJ13, to chip moves parallel to planar complexity IJ15, IJ33,, IJ34, surface the print head fabrication Friction IJ35, IJ36 surface. Drop Stiction ejection may still be normal to the surface. Membrane An actuator with a The Fabrication 1982 push high force but effective area of complexity Howkins U.S. Pat. No. small area is used the actuator Actuator 4,459,601 to push a stiff becomes the size membrane that is membrane area Difficulty in contact with the of integration in ink. a VLSI process Rotary The actuator Rotary Device IJ05, IJ08, causes the rotation levers may be complexity IJ13, IJ28 of some element, used to increase May have such a grill or travel friction at a pivot impeller Small chip point area requirements Bend The actuator bends A very Requires 1970 Kyser when energized. small change in the actuator to be et al U.S. Pat. No. This may be due to dimensions can made from at 3,946,398 differential be converted to a least two distinct 1973 thermal expansion, large motion. layers, or to have Stemme U.S. Pat. No. piezoelectric a thermal 3,747,120 expansion, difference across IJ03, IJ09, magnetostriction, the actuator IJ10, IJ19, IJ23, or other form of IJ24, IJ25, IJ29, relative IJ30, IJ31, IJ33, dimensional IJ34, IJ35 change. Swivel The actuator Allows Inefficient IJ06 swivels around a operation where coupling to the central pivot. This the net linear ink motion motion is suitable force on the where there are paddle is zero opposite forces Small chip applied to opposite area sides of the paddle, requirements e.g. Lorenz force. Straighten The actuator is Can be used Requires IJ26, IJ32 normally bent, and with shape careful balance straightens when memory alloys of stresses to energized. where the ensure that the austenic phase is quiescent bend is planar accurate Double The actuator bends One Difficult to IJ36, IJ37, bend in one direction actuator can be make the drops IJ38 when one element used to power ejected by both is energized, and two nozzles. bend directions bends the other Reduced identical. way when another chip size. A small element is Not efficiency loss energized. sensitive to compared to ambient equivalent single temperature bend actuators. Shear Energizing the Can Not readily 1985 actuator causes a increase the applicable to Fishbeck U.S. Pat. No. shear motion in the effective travel other actuator 4,584,590 actuator material. of piezoelectric mechanisms actuators Radial The actuator Relatively High force 1970 Zoltan constriction squeezes an ink easy to fabricate required U.S. Pat. No. 3,683,212 reservoir, forcing single nozzles Inefficient ink from a from glass Difficult to constricted nozzle. tubing as integrate with macroscopic VLSI processes structures Coil/ A coiled actuator Easy to Difficult to IJ17, IJ21, uncoil uncoils or coils fabricate as a fabricate for IJ34, IJ35 more tightly. The planar VLSI non-planar motion of the free process devices end of the actuator Small area Poor out-of- ejects the ink. required, plane stiffness therefore low cost Bow The actuator bows Can Maximum IJ16, IJ18, (or buckles) in the increase the travel is IJ27 middle when speed of travel constrained energized. Mechanically High force rigid required Push- Two actuators The Not readily IJ18 Pull control a shutter. structure is suitable for ink One actuator pulls pinned at both jets which the shutter, and the ends, so has a directly push the other pushes it. high out-of- ink plane rigidity Curl A set of actuators Good fluid Design IJ20, IJ42 inwards curl inwards to flow to the complexity reduce the volume region behind of ink that they the actuator enclose. increases efficiency Curl A set of actuators Relatively Relatively IJ43 outwards curl outwards, simple large chip area pressurizing ink in construction a chamber surrounding the actuators, and expelling ink from a nozzle in the chamber. Iris Multiple vanes High High IJ22 enclose a volume efficiency fabrication of ink. These Small chip complexity simultaneously area Not suitable rotate, reducing for pigmented the volume inks between the vanes. Acoustic The actuator The Large area 1993 vibration vibrates at a high actuator can be required for Hadimioglu et frequency. physically efficient al, EUP 550,192 distant from the operation at 1993 Elrod ink useful et al, EUP frequencies 572,220 Acoustic coupling and crosstalk Complex drive circuitry Poor control of drop volume and position None In various ink jet No moving Various Silverbrook, designs the parts other tradeoffs EP 0771 658 A2 actuator does not are required to and related move. eliminate patent moving parts applications Tone-jet

NOZZLE REFILL METHOD Description Advantages Disadvantages Examples Surface This is the normal Fabrication Low speed Thermal ink tension way that ink jets simplicity Surface jet are refilled. After Operational tension force Piezoelectric the actuator is simplicity relatively small ink jet energized, it compared to IJ01-IJ07, typically returns actuator force IJ10-IJ14, IJ16, rapidly to its Long refill IJ20, IJ22-IJ45 normal position. time usually This rapid return dominates the sucks in air total repetition through the nozzle rate opening. The ink surface tension at the nozzle then exerts a small force restoring the meniscus to a minimum area. This force refills the nozzle. Shuttered Ink to the nozzle High speed Requires IJ08, IJ13, oscillating chamber is Low common ink IJ15, IJ17, IJ18, ink provided at a actuator energy, pressure IJ19, IJ21 pressure pressure that as the actuator oscillator oscillates at twice need only open May not be the drop ejection or close the suitable for frequency. When a shutter, instead pigmented inks drop is to be of ejecting the ejected, the shutter ink drop is opened for 3 half cycles: drop ejection, actuator return, and refill. The shutter is then closed to prevent the nozzle chamber emptying during the next negative pressure cycle. Refill After the main High speed, Requires IJ09 actuator actuator has as the nozzle is two independent ejected a drop a actively refilled actuators per second (refill) nozzle actuator is energized. The refill actuator pushes ink into the nozzle chamber. The refill actuator returns slowly, to prevent its return from emptying the chamber again. Positive The ink is held a High refill Surface Silverbrook, ink slight positive rate, therefore a spill must be EP 0771 658 A2 pressure pressure. After the high drop prevented and related ink drop is ejected, repetition rate is Highly patent the nozzle possible hydrophobic applications chamber fills print head Alternative quickly as surface surfaces are for:, IJ01-IJ07, tension and ink required IJ10-IJ14, IJ16, pressure both IJ20, IJ22-IJ45 operate to refill the nozzle.

METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Description Advantages Disadvantages Examples Long The ink inlet Design Restricts Thermal ink inlet channel to the simplicity refill rate jet channel nozzle chamber is Operational May result Piezoelectric made long and simplicity in a relatively ink jet relatively narrow, Reduces large chip area IJ42, IJ43 relying on viscous crosstalk Only drag to reduce partially inlet back-flow. effective Positive The ink is under a Drop Requires a Silverbrook, ink positive pressure, selection and method (such as EP 0771 658 A2 pressure so that in the separation forces a nozzle rim or and related quiescent state can be reduced effective patent some of the ink Fast refill hydrophobizing, applications drop already time or both) to Possible protrudes from the prevent flooding operation of the nozzle. of the ejection following: IJ01-IJ07, This reduces the surface of the IJ09-IJ12, pressure in the print head. IJ14, IJ16, IJ20, nozzle chamber IJ22,, IJ23-IJ34, which is required IJ36-IJ41, IJ44 to eject a certain volume of ink. The reduction in chamber pressure results in a reduction in ink pushed out through the inlet. Baffle One or more The refill Design HP Thermal baffles are placed rate is not as complexity Ink Jet in the inlet ink restricted as the May Tektronix flow. When the long inlet increase piezoelectric ink actuator is method. fabrication jet energized, the Reduces complexity (e.g. rapid ink crosstalk Tektronix hot movement creates melt eddies which Piezoelectric restrict the flow print heads). through the inlet. The slower refill process is unrestricted, and does not result in eddies. Flexible In this method Significantly Not Canon flap recently disclosed reduces back- applicable to restricts by Canon, the flow for edge- most ink jet inlet expanding actuator shooter thermal configurations (bubble) pushes on ink jet devices Increased a flexible flap that fabrication restricts the inlet. complexity Inelastic deformation of polymer flap results in creep over extended use Inlet A filter is located Additional Restricts IJ04, IJ12, filter between the ink advantage of ink refill rate IJ24, IJ27, IJ29, inlet and the filtration May result IJ30 nozzle chamber. Ink filter in complex The filter has a may be construction multitude of small fabricated with holes or slots, no additional restricting ink process steps flow. The filter also removes particles which may block the nozzle. Small The ink inlet Design Restricts IJ02, IJ37, inlet channel to the simplicity refill rate IJ44 compared nozzle chamber May result to has a substantially in a relatively nozzle smaller cross large chip area section than that of Only the nozzle, partially resulting in easier effective ink egress out of the nozzle than out of the inlet. Inlet A secondary Increases Requires IJ09 shutter actuator controls speed of the ink- separate refill the position of a jet print head actuator and shutter, closing off operation drive circuit the ink inlet when the main actuator is energized. The inlet The method avoids Back-flow Requires IJ01, IJ03, is the problem of problem is careful design to 1J05, IJ06, IJ07, located inlet back-flow by eliminated minimize the IJ10, IJ11, IJ14, behind arranging the ink- negative IJ16, IJ22, IJ23, the ink- pushing surface of pressure behind IJ25, IJ28, IJ31, pushing the actuator the paddle IJ32, IJ33, IJ34, surface between the inlet IJ35, IJ36, IJ39, and the nozzle. IJ40, IJ41 Part of The actuator and a Significant Small IJ07, IJ20, the wall of the ink reductions in increase in IJ26, IJ38 actuator chamber are back-flow can be fabrication moves to arranged so that achieved complexity shut off the motion of the Compact the inlet actuator closes off designs possible the inlet. Nozzle In some Ink back- None Silverbrook, actuator configurations of flow problem is related to ink EP 0771 658 A2 does not ink jet, there is no eliminated back-flow on and related result in expansion or actuation patent ink back- movement of an applications flow actuator which Valve-jet may cause ink Tone-jet back-flow through the inlet.

NOZZLE CLEARING METHOD Description Advantages Disadvantages Examples Normal All of the nozzles No added May not be Most ink jet nozzle are fired complexity on sufficient to systems firing periodically, the print head displace dried IJ01, IJ02, before the ink has ink IJ03, IJ04, IJ05, a chance to dry. IJ06, IJ07, IJ09, When not in use IJ10, IJ11, IJ12, the nozzles are IJ14, IJ16, IJ20, sealed (capped) IJ22, IJ23, IJ24, against air. IJ25, IJ26, IJ27, The nozzle firing IJ28, IJ29, IJ30, is usually IJ31, IJ32, IJ33, performed during a IJ34, IJ36, IJ37, special clearing IJ38, IJ39, IJ40,, cycle, after first IJ41, IJ42, IJ43, moving the print IJ44,, IJ45 head to a cleaning station. Extra In systems which Can be Requires Silverbrook, power to heat the ink, but do highly effective higher drive EP 0771 658 A2 ink not boil it under if the heater is voltage for and related heater normal situations, adjacent to the clearing patent nozzle clearing can nozzle May require applications be achieved by larger drive over-powering the transistors heater and boiling ink at the nozzle. Rapid The actuator is Does not Effectiveness May be succession fired in rapid require extra depends used with: IJ01, of succession. In drive circuits on substantially IJ02, IJ03, IJ04, actuator some the print head upon the IJ05, IJ06, IJ07, pulses configurations, this Can be configuration of IJ09, IJ10, IJ11, may cause heat readily the ink jet nozzle IJ14, IJ16, IJ20, build-up at the controlled and IJ22, IJ23, IJ24, nozzle which boils initiated by IJ25, IJ27, IJ28, the ink, clearing digital logic IJ29, IJ30, IJ31, the nozzle. In other IJ32, IJ33, IJ34, situations, it may IJ36, IJ37, IJ38, cause sufficient IJ39, IJ40, IJ41, vibrations to IJ42, IJ43, IJ44, dislodge clogged IJ45 nozzles. Extra Where an actuator A simple Not suitable May be power to is not normally solution where where there is a used with: IJ03, ink driven to the limit applicable hard limit to IJ09, IJ16, IJ20, pushing of its motion, actuator IJ23, IJ24, IJ25, actuator nozzle clearing movement IJ27, IJ29, IJ30, may be assisted by IJ31, IJ32, IJ39, providing an IJ40, IJ41, IJ42, enhanced drive IJ43, IJ44, IJ45 signal to the actuator. Acoustic An ultrasonic A high High IJ08, IJ13, resonance wave is applied to nozzle clearing implementation IJ15, IJ17, IJ18, the ink chamber. capability can be cost if system IJ19, IJ21 This wave is of an achieved does not already appropriate May be include an amplitude and implemented at acoustic actuator frequency to cause very low cost in sufficient force at systems which the nozzle to clear already include blockages. This is acoustic easiest to achieve actuators if the ultrasonic wave is at a resonant frequency of the ink cavity. Nozzle A microfabricated Can clear Accurate Silverbrook, clearing plate is pushed severely clogged mechanical EP 0771 658 A2 plate against the nozzles alignment is and related nozzles. The plate required patent has a post for Moving applications every nozzle. A parts are post moves required through each There is nozzle, displacing risk of damage dried ink. to the nozzles Accurate fabrication is required Ink The pressure of the May be Requires May be pressure ink is temporarily effective where pressure pump used with all IJ pulse increased so that other methods or other pressure series ink jets ink streams from cannot be used actuator all of the nozzles. Expensive This may be used Wasteful of in conjunction ink with actuator energizing. Print A flexible ‘blade’ Effective Difficult to Many ink head is wiped across the for planar print use if print head jet systems wiper print head surface. head surfaces surface is non- The blade is Low cost planar or very usually fabricated fragile from a flexible Requires polymer, e.g. mechanical parts rubber or synthetic Blade can elastomer. wear out in high volume print systems Separate A separate heater Can be Fabrication Can be used ink is provided at the effective where complexity with many IJ boiling nozzle although other nozzle series ink jets heater the normal drop e- clearing methods ection mechanism cannot be used does not require it. Can be The heaters do not implemented at require individual no additional drive circuits, as cost in some ink many nozzles can jet be cleared configurations simultaneously, and no imaging is required.

NOZZLE PLATE CONSTRUCTION Description Advantages Disadvantages Examples Electro- A nozzle plate is Fabrication High Hewlett formed separately simplicity temperatures and Packard Thermal nickel fabricated from pressures are Ink jet electroformed required to bond nickel, and bonded nozzle plate to the print head Minimum chip. thickness constraints Differential thermal expansion Laser Individual nozzle No masks Each hole Canon ablated holes are ablated required must be Bubblejet or drilled by an intense UV Can be individually 1988 Sercel polymer laser in a nozzle quite fast formed et al., SPIE, Vol. plate, which is Some Special 998 Excimer typically a control over equipment Beam polymer such as nozzle profile is required Applications, pp. polyimide or possible Slow where 76-83 polysulphone Equipment there are many 1993 required is thousands of Watanabe et al., relatively low nozzles per print U.S. Pat. No. 5,208,604 cost head May produce thin burrs at exit holes Silicon A separate nozzle High Two part K. Bean, micro- plate is accuracy is construction IEEE machined micromachined attainable High cost Transactions on from single crystal Requires Electron silicon, and precision Devices, Vol. bonded to the print alignment ED-25, No. 10, head wafer. Nozzles 1978, pp 1185-1195 may be clogged Xerox 1990 by adhesive Hawkins et al., U.S. Pat. No. 4,899,181 Glass Fine glass No Very small 1970 Zoltan capillaries capillaries are expensive nozzle sizes are U.S. Pat. No. 3,683,212 drawn from glass equipment difficult to form tubing. This required Not suited method has been Simple to for mass used for making make single production individual nozzles, nozzles but is difficult to use for bulk manufacturing of print heads with thousands of nozzles. Monolithic, The nozzle plate is High Requires Silverbrook, surface deposited as a accuracy (<1 μm) sacrificial layer EP 0771 658 A2 micro- layer using Monolithic under the nozzle and related machined standard VLSI Low cost plate to form the patent using deposition Existing nozzle chamber applications VLSI techniques. processes can be Surface IJ01, IJ02, litho- Nozzles are etched used may be fragile to IJ04, IJ11, IJ12, graphic in the nozzle plate the touch IJ17, IJ18, IJ20, processes using VLSI IJ22, IJ24, IJ27, lithography and IJ28, IJ29, IJ30, etching. IJ31, IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Monolithic, The nozzle plate is High Requires IJ03, IJ05, etched a buried etch stop accuracy (<1 μm) long etch times IJ06, IJ07, IJ08, through in the wafer. Monolithic Requires a IJ09, IJ10, IJ13, substrate Nozzle chambers Low cost support wafer IJ14, IJ15, IJ16, are etched in the No IJ19, IJ21, IJ23, front of the wafer, differential IJ25, IJ26 and the wafer is expansion thinned from the back side. Nozzles are then etched in the etch stop layer. No Various methods No nozzles Difficult to Ricoh 1995 nozzle have been tried to to become control drop Sekiya et al U.S. Pat. No. plate eliminate the clogged position 5,412,413 nozzles entirely, to accurately 1993 prevent nozzle Crosstalk Hadimioglu et al clogging. These problems EUP 550,192 include thermal 1993 Elrod bubble et al EUP mechanisms and 572,220 acoustic lens mechanisms Trough Each drop ejector Reduced Drop firing IJ35 has a trough manufacturing direction is through which a complexity sensitive to paddle moves. Monolithic wicking. There is no nozzle plate. Nozzle The elimination of No nozzles Difficult to 1989 Saito slit nozzle holes and to become control drop et al U.S. Pat. No. instead replacement by a clogged position 4,799,068 of slit encompassing accurately individual many actuator Crosstalk nozzles positions reduces problems nozzle clogging, but increases crosstalk due to ink surface waves

DROP EJECTION DIRECTION Description Advantages Disadvantages Examples Edge Ink flow is along Simple Nozzles Canon (‘edge the surface of the construction limited to edge Bubblejet 1979 shooter’) chip, and ink drops No silicon High Endo et al GB are ejected from etching required resolution is patent 2,007,162 the chip edge. Good heat difficult Xerox sinking via Fast color heater-in-pit substrate printing requires 1990 Hawkins et Mechanically one print head al U.S. Pat. No. strong per color 4,899,181 Ease of chip Tone-jet handing Surface Ink flow is along No bulk Maximum Hewlett- (‘roof the surface of the silicon etching ink flow is Packard TIJ shooter’) chip, and ink drops required severely 1982 Vaught et are ejected from Silicon can restricted al U.S. Pat. No. the chip surface, make an 4,490,728 normal to the effective heat IJ02, IJ11, plane of the chip. sink IJ12, IJ20, IJ22 Mechanical strength Through Ink flow is through High ink Requires Silverbrook, chip, the chip, and ink flow bulk silicon EP 0771 658 A2 forward drops are ejected Suitable for etching and related (‘up from the front pagewidth print patent shooter’) surface of the chip. heads applications High nozzle IJ04, IJ17, packing density IJ18, IJ24, IJ27-IJ45 therefore low manufacturing cost Through Ink flow is through High ink Requires IJ01, IJ03, chip, the chip, and ink flow wafer thinning IJ05, IJ06, IJ07, reverse drops are ejected Suitable for Requires IJ08, IJ09, IJ10, (‘down from the rear pagewidth print special handling IJ13, IJ14, IJ15, shooter’) surface of the chip. heads during IJ16, IJ19, IJ21, High nozzle manufacture IJ23, IJ25, IJ26 packing density therefore low manufacturing cost Through Ink flow is through Suitable for Pagewidth Epson actuator the actuator, which piezoelectric print heads Stylus is not fabricated as print heads require several Tektronix part of the same thousand hot melt substrate as the connections to piezoelectric ink drive transistors. drive circuits jets Cannot be manufactured in standard CMOS fabs Complex assembly required

INK TYPE Description Advantages Disadvantages Examples Aqueous, Water based ink Environmentally Slow drying Most dye which typically friendly Corrosive existing ink jets contains: water, No odor Bleeds on All IJ series dye, surfactant, paper ink jets humectant, and May Silverbrook, biocide. strikethrough EP 0771 658 A2 Modern ink dyes Cockles and related have high water- paper patent fastness, light applications fastness Aqueous, Water based ink Environmentally Slow drying IJ02, IJ04, pigment which typically friendly Corrosive IJ21, IJ26, IJ27, contains: water, No odor Pigment IJ30 pigment, Reduced may clog Silverbrook, surfactant, bleed nozzles EP 0771 658 A2 humectant, and Reduced Pigment and related biocide. wicking may clog patent Pigments have an Reduced actuator applications advantage in strikethrough mechanisms Piezoelectric reduced bleed, Cockles ink-jets wicking and paper Thermal ink strikethrough. jets (with significant restrictions) Methyl MEK is a highly Very fast Odorous All IJ series Ethyl volatile solvent drying Flammable ink jets Ketone used for industrial Prints on (MEK) printing on various difficult surfaces substrates such such as aluminum as metals and cans. plastics Alcohol Alcohol based inks Fast drying Slight odor All IJ series (ethanol, can be used where Operates at Flammable ink jets 2- the printer must sub-freezing butanol, operate at temperatures and temperatures Reduced others) below the freezing paper cockle point of water. An Low cost example of this is in-camera consumer photographic printing. Phase The ink is solid at No drying High Tektronix change room temperature, time-ink viscosity hot melt (hot and is melted in instantly freezes Printed ink piezoelectric ink melt) the print head on the print typically has a jets before jetting. Hot medium ‘waxy’ feel 1989 melt inks are Almost any Printed Nowak U.S. Pat. No. usually wax based, print medium pages may 4,820,346 with a melting can be used ‘block’ All IJ series point around 80° C. No paper Ink ink jets After jetting cockle occurs temperature may the ink freezes No wicking be above the almost instantly occurs curie point of upon contacting No bleed permanent the print medium occurs magnets or a transfer roller. No Ink heaters strikethrough consume power occurs Long warm- up time Oil Oil based inks are High High All IJ series extensively used in solubility viscosity: this is ink jets offset printing. medium for a significant They have some dyes limitation for use advantages in Does not in ink jets, which improved cockle paper usually require a characteristics on Does not low viscosity. paper (especially wick through Some short no wicking or paper chain and multi- cockle). Oil branched oils soluble dies and have a pigments are sufficiently low required. viscosity. Slow drying Micro- A microemulsion Stops ink Viscosity All IJ series emulsion is a stable, self bleed higher than ink jets forming emulsion High dye water of oil, water, and solubility Cost is surfactant. The Water, oil, slightly higher characteristic drop and amphiphilic than water based size is less than soluble dies can ink 100 nm, and is be used High determined by the Can surfactant preferred curvature stabilize pigment concentration of the surfactant. suspensions required (around 5%) 

1. A method of processing, in a digital camera, an image captured by the camera, the method including the steps of: locating faces within the captured image by detecting regions of contiguous color which map a hue, saturation and value of the range of human face colors and passing the detected regions through heuristic tests which produce a resulting probability of a face being present in the image; locating eyes of the located faces; and determining if the captured image of the located eyes has been modified by the act of capturing the image, and if so, locating any unwanted distortions of the located eyes in the captured image that have occurred as a result of the act of capturing the image, and modifying the captured image to at least reduce the effect of the unwanted distortions and to produce a modified image.
 2. The method of claim 1 wherein the determining step includes determining if a flash was used in capturing the image.
 3. The method of claim 1 wherein said unwanted distortions include “red-eye” effects.
 4. The method of claim 1 wherein said unwanted distortions include reflections in the captured image.
 5. The method of claim 1 wherein said unwanted distortions include modification of the colors captured.
 6. The method of claim 1 further including adding at least one predetermined image to the captured image.
 7. The method of claim 1 wherein, if it is determined that the captured image has not been modified by the act of capturing the image, adding at least one predetermined image to the captured image.
 8. The method of claim 1 including storing at least one of the modified image and the captured image.
 9. The method of claim 1 including displaying at least one of the modified image and the captured image on a display of the camera. 